// PEEPHOLE OPTOMIZING Code ArrayList
import java.util.*;

class optimizer
{
    ArrayList<operation> Code;  // pointer to list in generator2
    int changes = 0;

    public optimizer(ArrayList<operation> a) {Code=a;}

    /* function to detect and simplify:

       push A
       pop register   to mov A,register
    */
    public void pushpop()
    {
	int i; 
	int n = Code.size();
	for(i=0;i<n-1;i++)
	    {
		operation a = Code.get(i);
		operation b = Code.get(i+1);
		if (a.opcode!=null && b.opcode!=null &&
		    (a.opcode.equals("push") || a.opcode.equals("pushl"))
		    &&
		    (b.opcode.equals("pop") || b.opcode.equals("popl"))
		    && 
		    (b.src instanceof register))
		    {
			Code.set(i,new operation("mov",a.src,b.src));
			Code.remove(i+1);  n--;  changes++;
		    }
	    } //for
    } //pushpop


    public void selfmove()
    {
	int i; 
	int n = Code.size();
	for(i=0;i<n;i++)
	    {
		operation a = Code.get(i);
		if (a.opcode!=null && 
		    (a.opcode.equals("mov") || a.opcode.equals("movl"))
		    && (a.src == a.dst))  // works for registers only
		    {
			Code.remove(i);  n--;
		    }
	    } //for
    }

    public void optimize()
    {
	pushpop();
	selfmove();
    }
} //optimizer